Bell Knife for Rotary Mower

ABSTRACT

A crop harvesting header has a cutter bed to cut crop material as the harvester advances through a field. The cutter bed includes a plurality of rotatable cutters having knives extending from opposing ends of the cutters. Each cutter has a generally elliptical knife carrier, and a pair of knives at opposites ends of the carrier, wherein a portion of each knife extends beyond the end of the carrier to expose a cutting surface to sever the standing crop. Each knife is shaped such that its width dimension at a proximal end where mounted on the knife carrier is narrower than its width dimension at a distal end extending away from the knife carrier.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of co-pending U.S. provisional application entitled “FIXED ROTARY KNIFE WITH MULTIPLE CUTTING SURFACES”, having Ser. No. 61/444,825, filed Feb. 21, 2011.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to crop harvesting machines of the type that use rotary cutters, and more particularly to rotary cutters having knives shaped to desirably expose the cutting surfaces used to sever the standing crop.

2. Description of Related Art

Wide cut rotary harvesters are commonly used to sever standing crops in the field and deposit the crop back onto the ground in the form of a windrow or swath to sever. It is known for harvesters to use a rotary style cutter bed located adjacent the front of the header framework for severing crop from the ground as the harvester moves across a field. For example, U.S. Pat. No. 6,158,201 to Pruitt et al. entitled “Rotary Mower Conditioner Having Improved Crop Flow” discloses a cutter bed that includes a series of rotary cutters spaced across the path of travel of the harvester and each being rotatable about its own upright axis. Typically, each of the cutters includes a generally elliptical, metal knife carrier and a pair of free swinging knives at opposites ends of the carrier.

Energy crops, such as sugar cane, grow in large clumps and the free swinging knives have a tendency to retract, resulting in poor cut off and excessive wear to the knife mounting hole and mounting components. It is desirable to have a clean cut with a minimum amount of shattering of the stubble. Based on the foregoing, it would be desirable to have a rotary header with improved cutters that present cutting surfaces at desired orientations with respect to the crop being cut.

OVERVIEW OF THE INVENTION

In one embodiment, the invention is directed to a cutter bed for a rotary mower used to sever standing crop as the cutter bed advances through a field. The cutter bed includes a plurality of rotatable cutters having knives extending from opposing ends of the cutters. Each cutter is ninety degrees out of phase with respect to its adjacent cutters such that the circular paths of travel of the knives of adjacent cutters overlap one another, and adjacent cutters rotate in opposite directions. Each cutter has a generally elliptical knife carrier, and a pair of knives at opposites ends of the carrier, wherein a portion of each knife extends beyond the end of the carrier to expose a cutting surface to sever the standing crop. Each knife is shaped such that its width dimension at a proximal end where mounted on the knife carrier is narrower than its width dimension at a distal end extending away from the knife carrier. Desirably, the width dimension at the distal end is between about 1.5 and 2.5 times the width dimension at the proximal end. In one embodiment, each knife is shaped such that its cutting surface is at an angle with respect to an axis of the carrier, wherein said angle is between about 10 degrees and about 45 degrees.

These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features of this invention will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 shows a perspective view of an example embodiment of a self-propelled windrower that may employ a rotary mower header in accordance with the invention.

FIG. 2 shows a top view of an example embodiment of a harvesting rotary mower header, with parts being broken away to illustrate the cutter bed;

FIG. 3 shows an enlarged perspective view of an embodiment of a cutter of the cutter bed of FIG. 2; and

FIG. 4 shows an enlarged, perspective view of the underside side of the cutter of FIG. 3.

Corresponding reference characters indicate corresponding parts throughout the views of the drawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The invention will now be described in the following detailed description with reference to the drawings, wherein preferred embodiments are described in detail to enable practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. But to the contrary, the invention includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following

DETAILED DESCRIPTION

FIG. 1 shows a harvester in the form of a self-propelled windrower 10 operable to mow and collect standing crop in the field, condition the cut material as it moves through the machine to improve its drying characteristics, and then return the conditioned material to the field in a windrow or swath. Although the invention will be described using a self-propelled windrower, one skilled in the art will understand that any self-propelled or pull-type rotary mower may utilize the invention disclosed herein. The windrower 10 may include a chassis or frame 12 supported by wheels 14 for movement across a field to be harvested. The frame 12 carries a cab 20, within which an operator controls operation of the windrower 10, and a rearwardly spaced compartment 22 housing a power source (not shown) such as an internal combustion engine. A harvesting header 24 is supported on the front of the frame 12 in a manner understood by those skilled in the art.

The header 24 may be similar to that disclosed in U.S. Pat. No. 6,158,201 to Pruitt et al. entitled “Rotary Mower Conditioner Having Improved Crop Flow” which is assigned to the assignee of the present invention and incorporated by reference in its entirety herein. The header 24 may be configured as a modular unit and consequently may be disconnected for removal from the frame 12. Accordingly, the frame 12 is not dedicated only to those harvesting operations provided by the header 24, but may carry other modular headers designed to perform different harvesting operations. Similarly, the header 24 may be removed from the frame 12 and installed on other variously constructed mobile frames, such as a pull-type implement. In this respect, it will be appreciated that the principles of the present invention are equally applicable to pull-type harvesting machines and machines dedicated only to mowing and conditioning crop.

Turning now to FIG. 2, the header 24 may have a generally open, box-like framework 32 that includes a pair of tubular cross beams 34 and 36 supported at opposite ends by side plates 38 and 40. A pair of shield supports 42 and 44 is fixed relative to the side plates 38 and 40 to project rearwardly therefrom. The shield supports 42, 44 converge rearwardly and support the windrow forming shields, generally denoted by the reference numeral 46 in FIG. 1. A pair of laterally extending, upright outboard plates 48 and 50 project outwardly beyond the cross beams 34 and 36, with the inner ends of the outboard plates 48 and 50 defining therebetween the front boundary of a discharge opening 52 through which cut crop passes as it moves rearwardly in the header 24.

A laterally extending crop cutting assembly in the form of a low profile, rotary style cutter bed 66 is located adjacent the front of the header framework 32 for severing crop from the ground as the harvester 10 moves across a field. The illustrated cutter bed 66 includes a series of ten rotary cutters 68 spaced across the path of travel of the harvester 10 and each being rotatable about its own upright axis. However, one skilled in the art will understand that a larger or smaller number of cutters 68 could be provided without departing from the scope of the invention. The cutters 68 are rotatably supported on an elongated, flat gear case 70 extending the full length of the cutter bed 66 to present a substantially planar cutting zone, within which crop is severed from the ground. The gear case 70 may contain a train of flat spur gears (not shown) that are operably engaged with one another and thus serve to distribute driving power between one another, although other forms of power distribution means may be used within the case 70 (e.g., shafts and bevel gears, belts and pulleys, or chains and sprockets).

Each of the cutters 68 may be ninety degrees out of phase with respect to the adjacent cutters, inasmuch as the circular paths of travel of the knives of adjacent cutters overlap one another and must be appropriately out of phase in order to avoid striking each other. Due to the positive mechanical drive connection between the cutters 68 through the spur gears in the case 70, the cutters remain properly in phase with one another. It will also be appreciated that the spur gears are arranged in such a manner that the inner cutters (excluding the outermost cutters) are divided into cooperating pairs, with the two cutters of each pair rotating in opposite directions. In other words, the second and third cutters 68 as viewed from the left end of the cutter bed 66 in FIG. 2 rotate toward one another across the front of the cutter bed 66, as do the fourth and fifth cutters, the sixth and seventh cutters, and the eighth and ninth cutters.

It will be appreciated that the cutters 68 are similar in construction. For the sake of brevity, only one of the cutters 68 will be described in detail herein with the understanding that the remaining cutters are similarly constructed. Turning now to FIG. 3, each of the cutters 68 may include a generally elliptical, metal knife carrier 72, and a pair of knives 74 at opposites ends of the carrier 72. A portion of each knife 74 extends beyond the end of the carrier 72 to expose a cutting surface 76 that is used to sever the standing crop as the rotating cutter 68 advances through the field. The carrier 72 has a center mounting portion 78 used to mount the cutter 68 on the gear case 70 (FIG. 2) as is well known in the art using sound engineering judgment.

As is known in the art, each knife 74 is attached to the carrier 72 with an attachment device 80. In one embodiment, the attachment device 80 comprises a bolt, screw or other suitable fastening device 82 positioned in a central portion of the knife 74 and aligned with an attachment hole 84 in the carrier 72. Desirably, the knife 74 is configured with two cutting surface 76. In use, the cutting surface 76 on the leading side of the knife 74 with respect to the direction of rotation of the cutter 68 is used to cut the crop material as the cutter bed 66 advances through the field. The attachment device 80 permits the knife 74 to be removed from the carrier 72 and repositioned by flipping the knife 74 upside down such that the opposing cutting surface 76 becomes the leading side and is exposed for cutting operations.

According to the invention, the knife is bell-shaped such that its width dimension at a proximal end 90 near the attachment device 80, designated in FIG. 4 by the dimension A, is narrower than its width dimension at a distal end 92 extending away from the carrier 72, designated by the dimension B. In the illustrated embodiment, the knife has a general trapezoid shape with the two cutting surfaces 76 being non-parallel sides 94. However, one skilled in the art will understand that the ends 90, 92 need not be parallel nor form straight lines. Desirably, dimension B at the distal end is between about 1.5 and 2.5 times the dimension A at the proximal end, and more preferably about 2 times the dimension A. It is believed that in robust energy crops such as sugar cane, as the cutter 68 rotates and the knives 74 strike the crop to be cut, the impact force has a tendency to cause the knives 74 to retract leading to poor cutoff and shattering of the stubble. The additional mass in the knife 74 at its distal end 92 tends to reduce retraction of the knife 74 as it passes through the crop. Additionally, with the bell-shape, even if the knives 74 retract slightly, the cutting surface 76 is desirably at least oriented perpendicular to the crop or inclined inward, which would have the tendency of pulling the crop into the cutter 68 instead of rejecting it. Desirably, the knife 74 is shaped such that the cutting surfaces 76 are at an angle a with respect to the axis T of the carrier 72 as seen in FIG. 4. Desirably, angle α is between about 10 degrees and about 45 degrees.

The foregoing has broadly outlined some of the more pertinent aspects and features of the present invention. These should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Other beneficial results can be obtained by applying the disclosed information in a different manner or by modifying the disclosed embodiments. Accordingly, other aspects and a more comprehensive understanding of the invention may be obtained by referring to the detailed description of the exemplary embodiments taken in conjunction with the accompanying drawings. 

1. A cutter bed for a rotary mower used to sever standing crop as the cutter bed advances through a field, the cutter bed comprising a plurality of rotatable cutters having knives extending from opposing ends of the cutters, wherein each cutter is ninety degrees out of phase with respect to its adjacent cutters such that the circular paths of travel of the knives of adjacent cutters overlap one another, and wherein adjacent cutters rotate in opposite directions, each cutter comprising: a generally elliptical knife carrier; and a pair of knives rotatably mounted at opposites ends of the knife carrier, a portion of each knife extending beyond the respective end of the knife carrier to expose a cutting surface to sever the standing crop, wherein each knife is shaped such that its width dimension at a proximal end where mounted on the knife carrier is narrower than its width dimension at a distal end extending away from the knife carrier.
 2. The cutter bed of claim 1 wherein each of the knives has knife has a trapezoid shape with the two cutting surfaces being non-parallel sides.
 3. The cutter bed of claim 1 wherein the width dimension at the distal end is between about 1.5 and 2.5 times the width dimension at the proximal end.
 4. The cutter bed of claim 1 wherein the knife carrier has a carrier axis defined by mounting points of the pair of knives on the carrier, and each knife is shaped such that the cutting surface is at an angle with respect to said axis of the carrier, wherein said angle is between about 10 degrees and about 45 degrees.
 5. A crop harvesting rotary header configured for attachment to a frame of a harvesting machine comprising the cutter bed of claim
 1. 